Year after year, high temperatures in hot summer months often lead to stress for both cattle and producers. Heat stress may slow productivity in a herd, but managing the effects and educating yourself on the hot topic may be worthwhile. 

Heating up

Four key factors that affect heat stress are temperature, humidity, wind speed and solar radiation, says A.J. Tarpoff, associate professor and beef extension veterinarian at Kansas State University. He explains those factors, along with the cattle’s accumulative heat load, contribute immensely to their comfort level in higher temperatures.

Cattle have an amazing ability to be able to accumulate heat during the day, but they do have to be able to dissipate that at night. In order for that to happen, they do need some comfortable nighttime cooling hours, between four to six hours.” — A.J. Tarpoff

Tarpoff says without proper time to cool down, cattle are not able to begin the following day with a clean slate. Instead they begin a backwards cycle where problems may occur. 

“The consequences of heat stress are really the coping behaviors of cattle to try to cool themselves,” Tarpoff explains. “The animal is in a thermoneutral zone where they’re most comfortable, they’re most productive. If they get out of that comfort zone, that’s where we have these coping behavior changes to help alleviate some of that heat.”

A notable coping mechanism is reduced dry matter intake. He explains while trying to cool themselves, cattle don’t have an appetite that increases their daily gain. Additionally, he says cattle may gather around water tanks, not necessarily consuming the water, but crowding nearby.

“All of these behaviors are not advantageous for growth and development,” he says. “They’re not eating, they’re standing longer than what they normally do, they have abnormal behaviors that really hinder performance.”

Cooling down

Addressing irregular coping behaviors doesn’t have to be complex. Simple solutions like adjusting management techniques already used on-farm can be easy and cost-efficient ways to manage heat stress. 

Tarpoff shares that simple necessities, like water and feed, should be monitored closely when managing heat stress.

“Water is the most essential nutrient to life, and water becomes extremely important during the summer months,” Tarpoff notes.

Cattle’s water intake increases with a rise in temperature, and it’s crucial plentiful water is always available. Tarpoff explains water needs may double on any given day in hot summer months, so providing a quality water source is key.

“Whether that’s increasing water tanks, pumping or having a cool water source available to them during those points of time, that’s a really critical piece,” he says.

The other essential in this equation is feed. Whether cattle are grazing or in a feedlot setting, he explains the digestion of feed will generate heat. Therefore, creating a mealtime routine that complements a cooler time of day will prevent overstimulation of daily heat-generating events. 

“Maybe we feed a little bit later into the evening hours, where we can have that heated digestion peak in the overnight cooling time and not have the additive effects during the day,” Tarpoff says.

While feed and water are the top priority, maximizing their environment can reduce the stress within animals significantly, according to Tarpoff. 

For cattle that reside in dirt pens, they are prone to the effects of heat absorbed by the dirt itself. 

“If we have a packed dirt pen during the heat of the day, it may get upwards to 140 degrees,” he says. “That’s pretty extreme.”

Utilizing bedding, like its usage in winter months, can provide relief to animals, as its reflective ability can reduce the heat up to 25°. 

“Shade’s a wonderful tool, too. It’s an investment in the animals and their well-being,” Tarpoff says. “If shade’s going to be utilized, critical care should be taken to ensure that there’s enough of it that all animals can utilize it at the same time without getting too packed.”

Finally, a fix that may come with questions is using sprinklers. Tarpoff explains there are several misconceptions with sprinklers, and it is not uncommon to see them used incorrectly in a feedyard. 

“Sprinklers should really be utilized to help cool the pen floor in the overnight hours, not to wet the animals during the heat of the day,” he says. 

A genetic approach

Keeping things simple and forming routines may help reduce the effects of heat stress. In the Angus breed, producers can plan even further and view solutions from a genetic standpoint. 

Kelli Retallick-Riley, president of Angus Genetics Inc. (AGI) explains that the hair shedding (HS) expected progeny difference (EPD) is targeted at helping producers breed more heat-tolerant cattle.  

“Early-summer hair shed was a trait that we started to capture not only for heat thermal tolerance, but also fescue toxicosis,” she mentions. 

She notes the hardy fescue grass may cause some issues in the Southeast region of the United States, where it is often utilized for long grazing cycles. 

“The issue with it is that it can form a fungi that can be toxic to our animals and actually can, with the same things with heat stress, can basically affect the overall fertility and performance of those females, especially as they wean off calves,” Retallick-Riley says.

She explains the HS EPD combats toxic fescue and can alleviate some effects of heat stress because as females shed their winter coats faster and earlier in the year, they are better able to tolerate hot conditions. 

With the evolution of the EPD, producers can now score females on a scale from 1 to 5 from the convenience a side-by-side cab or horseback. 

“It’s a fairly easy trait to measure. We don’t have to get cattle in the chute, we don’t have to do things like that from a management standpoint,” Retallick-Riley says.

As she points out, the breed takes the driver’s seat when it comes to innovating solutions for challenging environments and reduced productivity. Utilizing the HS EPD and simple solutions can reduce the consequences of heat stress. 

“Angus breeders have always been very keen on adapting new technologies, new scoring systems, new genetic tools, all those sorts of things,” she says. “It’s a testament to their commitment to working together as a group of association members to drive genetic progress forward.”